13
3.21 REQUIREMENTS FOR RECOVERY, REUSE
AND DISPOSAL
All consumables, parts like refrigerant, oil, heat transfer
medium, filters, driers, insulation materials, etc. should
be recovered, reused or disposed off in proper manner. It
is to be undertaken by competent person only.
There should be proper facility for disposal as per
regulatory rules and laws established by state/local
authorities to prevent person, property, society and
environment.
LIMITS OF PART LOAD OPERATION -
SINGLE STAGE COMPRESSOR
1. As a general rule, irrespective of refrigerant and
conditions of operations, it is advisable not to run
the compressor at minimum port condition for a
prolonged period of time.
2. In case of continuous part load operation of
ammonia refrigerant system, all existing standard
capacity control steps given in the tables can not be
used. There is a limitation, with respect to minimum
capacity, which depending on the amount of suction
superheat, is determined by maximum discharge
temperature of 140 deg C. This part load condition
can not be eliminated by applying cylinder head
water cooling system.
3. In case of R12. R22 & R502 there are least
possibilities of reaching discharge gas temperature
upto 140 deg C. Therefore. all capacity control steps
can be used for these refrigerants.
Only under very extreme conditions like, ambient
temperature is very high (more than 40 Deg C.) and
suction gas superheat is also very high (more than 30
Deg C.). this situation may occur that during part
load discharge temperature may reach to 140 Deg C
and/or oil temperature reaches to 70 Deg C. In this
case. It is not permitted to switch off the cylinder
down to standard minimum capacity step.
STANDARD CAPACITY CONTROL STEPS :
1. Ref figure no. 9 to 14 for single stage compressors.
2. Ref chapter no. 5 for two stage compressors.
4. CAPACITY CONTROL SYSTEM -
SINGLE STAGE COMPRESSOR
Capacity control system is used to balance the
compressor cooling capacity to the refrigeration load.
This is achieved by operating unloader piston valve
assembly by means of high pressure hydraulic 011
circuit through 3 way solenoid valves. This loading-
unloading of cylinder is explained in chapter No. 2
under heading "VALVE LIFTING MECHANISM".
The capacity control can be exercised by either manual
or automatic operation of 3 way solenoid valve.
In case of manual capacity control, the solenoid valves
are either manually actuated through toggle switch or
through mechanical manual over-ride provided to
solenoid valve.
In case of automatic control, the solenoid valves are
actuated by electrical remote control source. This
electrical remote control source may be a temperature
sensing device Installed in the space to be cooled or may
be LP pressostat fitted to refrigeration system.
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